关键词: 可搜索加密, 隐藏向量加密, 指定验证者, 代理重加密, 代理权限可撤销

Abstract: Hidden vector encryption (HVE) is a notable case of predicate encryption that enables the fine-grained control on the decryption key and supports the conjunctive keyword search and range queries on encrypted data. Such a technology can play an important role in the electronic health record (EHR) system since it incorporates the security protection and the convenience searchable functions on the sensitive medical records. However, all the existing HVE schemes cannot provide designed tester and automatically delegation function while requiring a low communication and computation overhead. In this paper, an efficient HVE scheme with designed tester and timing controlled proxy re-encryption is proposed. The delegatee can perform search operation on the re-encryption ciphertext during a certain period of time specified by the delegator, and the search authority can be revoked automatically after the effective time period. Since only the designed tester can test whether the given query tokens match the ciphertext, the proposed scheme can also resist the off-line keyword guessing (KG) attack. Moreover, our scheme is proved secure against chosen keyword and chosen time attack in the standard model and maintains a relatively low asymptotic complexity because it only requires a token size of O(1) and O(1) bilinear pairing computations in the test process.

Key words: searchable encryption, hidden vector encryption (HVE), designed tester, proxy re-encryption, revocable proxy